Rubber article and method of making the same



Nov. 23, 1943. G. L. 'WINDER RUBBER-ARTICLE AND METHOD OF MAKING THE SAME Filed May 9, 1941 2 Sheets-Sheet 1- DU /7723a;

550? E L Mhdea 6.3L. WINDER 2,335,203

RUBBER ARTICLE AND marten 01;- 111mm missus Nov. 23, 1943.

Filed lay 9,1941

2 Sheets-Sheet 2 Patented Nov. 23, 1943 RUBBER ARTICLE MAKING George L. "Winder,

or to American Anod rotation of Delaware AND METHOD OF THE SAME Cuyahoga Falls, Ohio, assign- 1: Inc., Akron, Ohio, a cor- Applicatlon May 9, 1941. Serial No. 392,600

11 Claims.

This invention relates to hollow rubber articles provided with communicating tubes extending therefrom and especially to blood pressure bags embodying novel constructional features and to economical and eiiicient procedure for manufacturing such articles. The invention will be described in detail with reference to the accompanying drawings of which:

Fig.1 is a sectional elevation illustrating a prellmlnary step in the manufacture of a tube assembly employed in the present invention and showing an auxiliary deposition form immersed in a liquid rubber composition for receiving a coating or rubber.

Fig. 2 is a perspective view illustrating a further step in the process and showing the tube assembly being removed from the auxiliary deposition form.

Fig. 3 is a sectional elevation illustrating a further step in the process and showing the tube assembly associated with a principal deposition form and the composite assembly immersed in a liquid rubber composition for receiving a coating of rubber.

Fig. 4 is a perspective view showing the composite assembly of Fig. 3 with a rubber coating thereon and further'illustrating the step of siltting a portion of the coating to permit removal of theprincipal form.

Fig. 5 is an elevation illustrating the step of removing the rubber coating from the principal deposition form.

Fig. 6 is a perspective view, partially broken away and sectioned for clarity of illustration, showing the coating after removal from the principal form and further illustrating a preliminary step in sealing the slit in the coating.

Fig. 7 is a sectional elevation illustrating a further step in sealing the slit and showing an end portion of the coating immersed in a liquid rubber composition.

Fig. 8 is a perspective view showing a finished blood pressure bag made in accordance withthe present invention.

Fig. 9 is a vertical section taken on line 9-9 of Fig. 5.

Fig. 10 is a fragmentary elevation, broken away and sectioned, showing an end-portion of a blood pressure bag embodying a modification of the in vention in which a reinforcing element is included in the region of the slit.

Fig. 11 is a perspective view in a modified procedure for to the end portion of a bag.

Fig. 12 is a fragmentary perspectivgvlew show.-

illustratins a step applying a sealing cap known in the art as ing a finished bag with a sealing cap produced thereon in accordance with the modified method, portions 'of the bag being broken away and sectioned for clarity of illustration.

Equipment used by physicians for determining the blood pressure of patients includes a unit a blood pressure bag. Such blood pressure bags customarily are made of rubber or analogous material and include a generallly rectangular flat hollow bag B and a pair of communicating tubes T, T extending from one of the longer edges of the bag at a. position adjacent one end thereof as indicated in Fig. 8. According to the present invention, such a blood pres-- sure bag is made by a process in which a tube assembly is first formed independently, after which the bag portion is formed in contiguous cohering relation with a portion of the tube assembly. The invention also contemplates a novel procedure for sealing a slit in a rubber member such as a rubber bag as well as the sealed rubber article produced in accordance with the novel sealing procedure.

To form the tube assembly, I utilize an auxiliary deposition form indicated generally by the numeral ill. The auxiliary form i0 includes a relatively small trapezoidal plate member I I provided with two rod-like stems l2,. l2 extending from one edge of the plate member II in the plane 01' the plate, the stems l2 corresponding in size and length to the interior diameter and length 01' the tubes desired in the blood pressure bag. The form Hl may have a supporting member such as the hookl3 of the plate. To produce the tube assembly, the auxiliary form I0 is coated with rubber as by immersing the form in a liquid rubber composition such as any suitably compounded latex L as illustrated in Fig. 1. Desirably the form In is precoated with a composition adapted to coagulate latex compositions asdescribed in U. S. Patent No. 1,908,719, and such coagulant composition deslrably should contain a powdery separating material as described in U. S. Patent No. 1,924,214. The form It is completely immersed in the latex as shown in Fig. 1 and is permitted to remain therein until a rubber deposit from .015 to .025" thick (when finished) has been deposited over the entire form. The form then desirably is raised until the liquid level of the latex is just below the edge of the plate member II and deposition on the immersed stems I2 is then continued until the total rubber deposit on the stems is from .030 to .060" thick (when finished). Such continued deposition may be effected by progressive extending from the opposite edge what longer than the exposed portions action of coagulant initially applied to the form, or the stems I2 may be re-dipped a number of times, either with or without intermediate coagulant treatments, to build up the desired thickness of rubber. deposited rubber coating is then removed from the latex and the rubber deposit is dried but not vulcanized. The rubber coating is then slit around the top edge of the plate II to permit removing the tube assembly from the form as shown in Fig. 2, after which the ends of the tubes'are opened by cutting off the closed ends as indicated at 24, 24.

It will be appreciated that the tube assembly so produced comprises a pair of relatively long rubber tubes l4, M which terminate in a flaring, flange-like member I5 comprising two generally parallel flaps. the flaring member l5 will constitute a reinforcing element in thefinished bag. To insure a neat product, the exposed end of the element l5 desirably should be trimmed smoothly as along the semi-circular dotted line shown in Fig.2 and indicated by the numeral I6.

I then providea principal deposition form including a main portion H of generally flat rectangular configuration adapted to form the bag portion of the final product. The principal form also is provided withtwo rod-like stemslB, H which extend outwardly inthe plane of the form from one of the longeredges of the main portion I! at a position adjacent one end thereof as shown in Fig. 3. The stems I8 desirably should be somerubber tubes M of the preparedtube assembly, but otherwise should correspond in size to the tubes.

I next'place the prepared tube assembly on the principal form by sliding the tubes H down over the stems l8 until the flaring flange or reinforcing element l5 embraces closely the portion of the main form adjacent the bases of the stems l8 as may be seen more clearly in Fig. 3. Desirably the underside of the reinforcing element I5 is cemented to theform II by means of a thin coating of rubber cement or other suitable adhesive which will prevent seepage of liquid rubber composition between the two members during subsequent operations while permitting ready removal of the completed article including the element IS. A suitable supporting clamp I9 is then attached to the extending ends of the stems l8 and the composite assembly of the principal form with the tube assembly thereon is immersed in a liquid rubber composition, such as a suitably compounded rubber latex L, and a coating of rubber 25, for example, about .025" thick is deposited over the entire assembly including the of the principal form and the The form l0 together with the.

form as shown in Fig. 5, and stripping the tubes from the stems.

To seal the opening made by the slit, the cut edges at the slit preferably are coated with rubber cement or other rubber adhesive as indicated at 2| (Fig. 6) and the cemented edges are pressed As will appear more clearly later, 1

outer surfaces of the tube assembly. As before,

such deposition may be facilitated by the use of any appropriate coagulant for latex. The assembly with its over-all coating of rubber is then removed from the latex and the rubber is dried. but not vulcanized-.- Y

To permit removal of the principal form, I then slit a portion of the rubber deposit 25, preferably along the major length of the shorter edge of the deposit removed from the tube assembly. Such slitting conveniently may be accomplished simply by progressively pressing a heated cutting element 20 or other suitable instrument against the rubber along the edge (Fig. 4). The principal form is then removed through the opening made by the slit by doubling the rubber coating back over the into abutting relation. To insure against leakage at the seal and to reinforce the seal against failure when the bag is inflated, a reinforcing cap of rubber 22 is produced thereover as by immersing the end portion, for example about one inch, of the bag in latex L or other liquid rubber composition as shown in Fig. 7. This procedure may be repeated several times to build up a rubber cap of any desired thickness;

Finally, the entire article is thoroughly dried and vulcanized by heating in the usual manner to produce a finished blood pressure bag as shown in Fig. 8. v

For fu ther reinforcing the seal at the slit, when desired, a strip of textile fabric 23 (Fig. 10) or other reinforcing material may be placed over the slit prior to application of the rubber cap 22, or the fabric strip may be interposed between any of the successive deposits constituting the cap 22. In either case, the fabric 23 preferably is pre-treated with latex or other rubber composition'to secure more perfect anchorage in the rubber. V g

It will be appreciated from the foregoing that a blood pressure bag or other article produced according to the present invention includes a hollow bag portion B with two communicating tubes T, T, extending therefrom and that the reinforcing element 15 is attached to the interior face of the wall 25 of the bag and is continuous with the inner portion H of the tubes T, as more clearly shown in Fig. 9. The outer portions of the tubes T are continuous with the wall 25 of the bag B so that an unusually strong and essentially unitary structure is produced which effectively resists failure heretofore experienced at the Junction between the tubes and the bag. Furthermore, the products of the present invention include a reinforcing cap over the slit at the end of the bag which insures effective sealing and reinforcement against failure upon inflation. The cap also serves to provide a balanced appearance. It will further be appreciated that the constituent parts of the articles cohere and form an essentially unitary structure, although the several individual parts may still be identified in the finished product.

As indicated above, in order to build up a reinforcing and sealing cap 22 of the required thickness, it is necessary to dip the end of the bag in latex several times. It has been proposed to overcome this time-consuming feature by first treating the end of the bag to be coated with a coagulant material and then dipping in latex only once to build up the desired thickness. While such procedure will produce a satisfactory sealing cap at a single dipping, it has been found that when such a cap is dried and vulcanized the rubber deposit shrinks and causes the end of the bag to bow inward. Such inward bowing detracts greatly from the appearance and sales value of the bag. A method has now been devised whereby an entirely satisfactory sealing cap may be produced on the bags at a single dip but without involving any such tendency toward inward bowing of the ends. This result is accomplished by "producing a reinforcing and sealing cap having -cluding the slit against -a surface which has aluminum, or other suitable plate being relatively thinner. Such a cap may be produced by applying a narrow stripe of coagulant material to the edge surface of the bag member along the slit and then immersing the end portion of the bag in latex or other coagulable liquid rubber compositioin As the edges of the bag member normally are rounded transversely and as the slit usually is made along the peak of the transversely rounded edge, the required narrow stripe of coagulant material conveniently may be applied simply by pressing the edge region inbeen coated with the coagulant material. Such pro cedure is illustrated in Fig. 11 in which a glass, 28 is coated with coagulant composition indicated by the stippling 29. A suitable coagulant composition for this purpose maybe prepared by mixing 400 grams of calcium nitrate and 50 grams of ethyl lactate in one liter of denatured alcohol. A

quantity of such a composition should be spread on a plate in a thin film and the slit end of the shown in rounding of rial will be g. 11. By reason of the transverse the end of the bag, coagulant mateapplied in a stripe covering only a narrow zone including and surrounding the slit. the bag is then dipped in 'sufllcient to produce in the narrow zone overlying the stripe of coagulant a deposit of rubber member formed of rubber material having a seam therein and a sealing layer of rubber material bag B prgsised vertically against the plate as g having about the same thickness as'that of the walls 25, i. e., about .025" thick when dried. The rest of the deposit, of course, will be much thinner and will-gradually taper off to a feather edge at the margins. After drying and vulcanization, the finished article illustrated in Fig. 12 will comprise a sealing cap 30 of rubber solids overlying the slit and adjacent portions of the bag. The sealing cap will have a locally thickened zone directly overlying the slit as indicated by the numeral 3| but will taper off rapidly in all direc-- tions therefrom to feather edges at the margins indicated by the numerals 32. Such a cap provides efllcient and dependable sealing of the slit and is entirely free of the undesirable tendency to bow inward which has characterized prior efforts to use coagulants'.in this connection, Furthermore, the featherededges of the sealing member which comprises cap merge smoothly into the main body of the Y bag without producing abrupt lines in the surface and for this reason the finished bag made by the modified procedure presents a generally more pleasing/appearance.

The term "rubber has been used in a generic sense to include not only natural Hevea rubber but also, all analogous natural and synthetic rubbrs and rubber-like materials. While the invention has been described in considerable detail in connection with the manufacture of blood pressure bags, the principles herein set out obviously may be appliedwith advantage in the manufacture of numerous other articles. a It will likewise be understood that many modifications and variations in details of the procedure departing from the spirit and scope of the invention as defined bythe appended claims.

This application is a continuation-in-part of stantial portion of the exteriorly covering said seam and adjacent surface portions of the member, said sealing layer having a locally thickened portion in a zone overlying the seam.

2. An article of manufacture comprising. a member formed of rubber material having a seam therein and a sealing layer of rubber material exteriorly covering said seam and adjacent surface portions of the'member, said sealing layer being relatively thick in a narrow zone overlying the seam and tapering off, to a relatively thinfeather side thereof to a relatively thin feather edge.

like member formed of rubber material having a thin flat rectangular configuration whereby the edge portions of the member are relatively nar- 4. An article of manufacture comprising a bagrow and having aseam extending through subv stantially the full length of one of said edge porand a sealing layer of rubber material formtions, ing a cap exteriorly covering said seam and ad- Jacent surface portions of the bag-like member, said sealing layer being relatively thick in a narrow'zone overlying the seam and'tapering off in all directions to a thin feather edge.

5. An article of manufacture comprising a baglike member formed of rubber material having a thin flat rectangular configuration whereby the edge portion of the bag are relativelynarrow and having a seam extending through substantially the full lengthof an end edge portion of the bag, and a sealing layer of rubber material forming an integrally attached cap exteriorly covering said seam-and adjacent surface portions of the bag, said sealing layer being relatively thick in a narrow zone overlying the seam and tapering oif inall directions to a thin feather edge.

- 6. The method of sealing a slit in a rubber applying a narrow stripe the surface of the mem immersing at least a submember including the slit rubber composition, where- I of rubber material is produced over the slit and adjacent surface portions of the-member, the sealing deposit being materially thicker in a local zone overlying the slit of coagulant material to ber along the slit, and

in a coagulable liquid than in other portions of the deposit.

.and materials described may be eifected without posit of rubber 7. The method of sealing a slit in a rubber member which comprises applying a narrow stripe of coagulant material to the surface of the member along the slit by contacting a local zone of the said surface including the slit with a surface coated with the coagulant material, and thereafter immersing at least a substantial portion of the member including the slit in a coagulable liquid rubber composition, whereby a sealing dematerial is produced over the slit. and adjacent surface portions of the member, the sealing deposit being materially thicker in a local zone overlying the slit than in other por-. tions of the deposit.

slit than 8. The method of sealing a slit in an edge portionof a bag-like member which comprises applying a narrow stripe of coagulant material to the edge surface of the bag-like member along the slit, and thereafter immersing a determinate local end portion of the bag-like member including the slit and a narrow zone surrounding the slit in a coagulable liquid rubber composition, whereby a sealing deposit of rubber material forming a cap isproduced over the slit and surrounding surface portions of the bag-like membenthe sealing deposit being materially thicker in a local zone overinother portions. of. the. de-

zapply a narrow stripe 9;: The'metliod' ofsealing; a slit in an edge portiozr oiaiiiag-like member which comprisesapplyofcoagulantmaterial to the aznarrow' "stripe" edge. surface'of the bag-like member along the a'gul'ant material; terminate local and -ber; includingithe slit and a narrow zone surrounding the slit composition, whereby a sealing deposit of rubber material forming a cap is produced over the slit and thereafter-immersing a; de

and surrounding surface portions of the bag-like member, the sealing deposit being materially thicker in a local zone overlying the slit than in other portions of the deposit.

in a coagulable liquid rubber.

. slitby cohtacfinga restricted locaizon of the 4 said; surface witrna. surface coatediwith the ctrapply a narrow str' ipeoii the realm: and: immersing only a. determinatelocal end portion of tllEibagffik member:

including the slit. in a; coagulable ,liquidruhber composition to form thereon a sealing deposit; of

portion of the bag-like meme 10.- Inthe manufacture of .a bag-like rubber article, the process which includes the steps of producing a bag-like member of rubber material having a transversely rounded narrow edge, slitting the rounded edge longitudinally substantially along the peak thereof, contacting th slit-zone with a surface comprising coagulant material to to the slit region, and immersing at least a substantial portion of the ing the slit in a coagulable liquid rubber composition to form. thereon a sealing deposit of rubber material having a locally thickened zone overlying the slit. 4

11. In the manufacture of a bag-like rubber article',,-the process which includes the steps of.

"producing a bag-like memberoirubbeymaterial 7 having a transversely rounded narrow edge. slittingthe ruundedeeeeieneitudineuysubstantiall contacting: the "silt zone.

rubbermateriai forming a cap having a locally duichened zone overlying the slit.

Gnome L. WIN-Em.

of the coagulant material bag-like member includ- 

